94 CHECK LIST OF THE 



less enlarged spinous plates or ctenoid scales, which in most species fall 

 off at intervals, leaving a naked strip, in some species persistent and but 

 slightly enlarged ; sides of head scaly or not ; lateral line complete or 

 nearly so ; fins large, the soft dorsal smaller than the spinous or the anal ; 

 anal spines two (one of them very rarely obsolete) ; dorsal spines ten to 

 fifteen ; ventral fins more or less widely separated, specially in species with 

 caducous plates. Parietal region more or less depressed, not strongly 

 convex in cross section ; supraoccipital crest usually present, but small. 

 Pyloric caeca, two to four. 



SUBGENUS ALVORDIUS. 



(99) Black-sided Darter. 



(Hadropterus aspro.) 



Body slender, fusiform, elongate ; head rather long and pointed ; the 

 maxilla extends slightly past front of eye ; the mandible is included ; the 

 eye large ; gill membranes slightly connected ; nape scaly or naked ; cheeks 

 with very small scales ; large scales on opercles ; caudal peduncle rather 

 long and slender ; caudal fin slightly emarginate. 



D. XII. to XV., ii to 13; A. II., 8 to 10. Scales, 9-65 to 80-17. 



Colour, greenish yellow with dark tessellations and marblings above, 

 and about seven large blotches along the side which are more or less con- 

 fluent ; fins barred and there is a small spot at base of caudal. Length 

 three to four inches. 



As this species is said to range all through the Great Lakes region 

 westward to Manitoba, it probably occurs here, though I have not as yet 

 found it. 



It frequents clear streams with gravelly bottoms and is more active 

 in its habits than most of the other Darters, not concealing itself so closely 

 under stones. 



GENUS COTTOGASTER. 



Body rather robust, little compressed ; head moderate, bluntish ; 

 mouth moderate or small ; the lower jaw included ; premaxillaries pro- 

 tractile or occasionally joined by a narrow frenum to the frontal region ; 

 maxillary not adherent to the preorbital ; teeth on vomer, gill membranes 

 nearly separate ; scales ctenoid ; the middle line of the belly anteriorly 

 naked or with caducous scales ; lateral line continuous ; dorsal fins large, 

 the second usually smaller than the first and smaller than the anal ; anal 

 spines two, the first the longer ; pyloric caeca three ; skull short, the 

 frontal region not very narrow, parietals little convex transversely, sutures 

 distinct ; no supraoccipital crest. 



